The field of the this invention is to perfusion pumps for use in angioplasty procedures.
Peristaltic pumps, used for pumping blood during open-heart surgery, do not have the capacity to generate pressures that are sufficient to force human blood through the relatively small lumens that are available in angioplasty balloon catheters.
U.S. Pat. No. 5,066,282 discloses a Positive Displacement Piston Driven Blood Pump for use during angioplasty. The invention of this patent is a single acting pump that includes an accumulation chamber having a membrane that functions to smooth out the pulsations of the single acting pump. The accumulation chamber must be filled with liquid and thus increases the total volume of fluid that is required to fill the system which adds to the weight and size of the pump. In addition to the pump a driver component is required and when combined this complex pump unit is relatively large and cumbersome and inconvenient for use in an operating room environment. In the preparation of a heart pump for use any air in the internal cavity of the pump must be removed to eliminate the possibility of pumping air into the patients blood stream. This preparation process becomes more difficult and time consuming as the volume of the internal cavity of the pump increases. In column 4, lines 9-14 of this patent, a double-acting arrangement is mentioned however such an arrangement is not described in full, clear and exact terms.
Because blood pumps are in direct contact with blood, in order to avoid spreading disease they cannot be reused and thus must be disposal. For this reason it is important that the cost of heart pumps be kept to a minimum.
Hemolysis, the breakdown of red blood cells, occurs normally when red blood cells lose their elasticity at the end of their life span. However, hemolysis may occur under many other circumstances such as when the blood is exposed to excessive shearing action as the result of greater than normal blood pressures, confining the blood flow to very small lumens and thus forcing the blood to flow at excessive flow rates and causing the blood to abruptly change its flow direction. Some hemolysis occurs when blood is forced to flow through the very small lumens available in an angioplasty catheter. The objective of this invention is to provide a simple blood perfusion pump, that can be manually powered with a minimum of effort, and can pump blood through an angioplasty catheter and balloon while minimizing hemolysis. In order to minimize hemolysis in the pump the conduits within the pump must be smooth, relatively large and shaped to accommodate directional changes in the blood flow path to thereby insure laminar flow and minimize turbulence and shear forces acting on the blood.